| 摘要 |
PROBLEM TO BE SOLVED: To reduce mold release resistance of an injection-molded impeller. SOLUTION: A blade 13 to partition a blade groove 12 of an impeller 7 is formed such that a radially internal part 20a of a surface 20 on the side situated upper stream of a rotation direction parallels to a central line CL and meanwhile, a radially external part 20b of the surface 20 on the side situated upper stream of a rotation direction is inclined forward. Further, the blade 13 is formed that the whole of a surface 21 on the side situated downstream of a rotation direction parallels to the central line CL. Thus, even when the impeller 7 is contracted for deformation after injection-molding, since a part to fasten a mold is only the forward inclination part of the blade 13, mold release resistance is decreased compared with a conventional example that the mold is nipped between the wholes of the surface 20 on the side, situated upper stream of a rotation direction, of the blade 13 and the surface 21 on the side, situated downstream of a rotation direction, of thereof.
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